Watchcase receiver



May 25 1926. 1,585,699

J. A. sTlRLlNG WATCHCASE RECEIVER Filed Dec. 1, 1924 Patented May 25,1926.

UNITED S'IATE-sv PATENT OFFICE.

N JAMES A. sT1nLrNG,'- or ELKHART', 1NDIANA,fAssIGNoR, BY MEsNEASSIGNMENTS, To CHICAGO TELEPHONE SUPPLY COMPANY, or ELKHART, INDIANA, ACORPORATION F DELAWARE.

WATCHCASE RECEIVER.

Application led December 1, 1924. Serial No. 753,323.

My invention relates to telephony and more particularly to a telephonereceiver of the watch case type. I

Receivers Ot this general type are now commonly employed in the head setor head phones for'radio reception.

It is desirable, to make the head phone as light as isconsistent withgood r-eception- It is also highly'desirable to have the receivenas forthe convenience of the wearer.

sensitive as possible and to secure, as nearly as possible, uniformityin, the output in order that the two receivers of a given head set maybematched in tone and receiving characteristics.

It is furthermore highly desirable to de sign the parts of a device ofthis character so that assembly may be accomplished in a simple andinexpensive manner with .the

assurance that-the resulting structure will be properly and permanentlyassembled and that the successive units of assembly will be uniform incharacter,

According to my invention, I provide a 5 metal aluminum shell or casewhich has its plate improves very decidedly 'the quality of`reception ofthe receiver, being spaced closeto the diaphragm and operating like asoundingboard on the sound waves generated by the moving diaphragm. Themagnetic systemis mounted on this tone plate and is otherwise free ofcontact with the vstress upon the diaphragm, and uniformity.

of tone in sound production.

I provide other incidental mechanical improvements which will beapparent from the following detailed specification. f

In the accompanying drawings I have illustrated an embodiment of myinvention which will teach those skilled in the art how to construct andoperate a device in accordance with my invention.

In the drawings: Figure n1 is a planview of a device showlng thediaphragm removed and ythe gear speed in section. This figure is takenon the line 1 1 of Fig. 3;

Fig. 2 is a section taken On the line 2-2 of Fig? 3, showing the magnetsystem in ,bottom plan View;

F ig."3 lis a transverse section taken on the line 3-3of Fig. 1;

` F ig. 4 is a transverse section taken at right angles thereto and. onthe line 4-4 indicated in Fig. 1;'

Fig. 5 is an isometric View of one of the pole pieces;

Fig. 8 is a fragmentary section through 80 one of the inserts in theterminal block; and

- Fig. 9 is a diagrammatic illustration oi. an

embodiment of the illustration.

lustrate my invention comprises 'a shell 10 which is drawn sheetaluminumof approximately 14 gauge. This shell has a back or bottom plate11 with a cylindrical rim dared out as indicated at 12 to a largerdiameter providing the threaded portion 13. The inside Of the threadedportion lis carefully finished to the desired diameter andthe threadedportion 13 is adapted to receive the threads of the cap 14, which cap isscrewed Adown to hold the diaphragm 15 and the The -receiver which .Ihave selected to ill tone plate 16 with its connected parts inposition.` The tone plate 16, which also may be termed an assemblyplate, has a raised rim17 which is stamped up1 about a 32nd of an inchabove the central portion of the .plate This plate 16 also has a centralaperture18 through which project the free ends or upright ends of 'thepole pieces 19. The plate 16 has three screw holes 20, 21 and' 22therethrough, which are threaded ,to receive clamping screws 23, 24 and25, respectively, for holding the magnet'system and the terminal bloei,respectively, upon the assembly terminal block 28 to hold the sameagainst.v

rotation. The terminal block 28 is made up of a pair of stampings offibre, or the like; with the screws passed through thecenter of the sameand holding the block upon the late 16. The terminals themselves areormed of sheet metal washers 29 having the integral ears 30 to which areconnecte CFI the ends of the windings of the coils. These terminalwashers 29 are held in place upon the block 28 by means of an insert 31which is formed of a threaded brass thimble, the outside of which isknurled. This thimble is pushed into registering openings in the twoparts of the terminal block 28 to hold the same together. The sleeve 31has a head which engages the washer 29 and holds the same firmly inelectrical and mechanical Contact. Suitable screws 32 are threaded intothe sleeves 31 and the terminals of the flexible cord 33 are fastenedunder said screws 32. The casing or shell 10 has an aperture at 34 forthe flexible cord shown at 33.

It will now be'seen that by means of the single screw 25 threaded intothe hole 22 in the plate 16, and the struck up lugs 27, the terminalblock 28 is held firmly in position upon the plate 16.

The magnet system which is assembled.

upon the plate 16, comprises the permanent horse-shoe magnet 35 formedpreferably of rectangular cross section with the 'sides` thereof groundparallel. This magnet is bent into circular form and the ends thereofhave openings through which the screws 23 and 24 pass to mount themagnet system upon the assembly or tone plate 16. f'

The pole pieces of the magnets 35 are separated from the assembly plate16 by means of the collars oi'posts 36 which serve to bring the ends orupright parts of the pole pieces 9 the proper distance fromthe'diaphragm 15. As heretofore explained, the magnets 35 arecarefullyground to size.

The pole pieces 19 comprise the base portion 38 and the upright endportions 39. The base portion 38 is provided with a hole 40 throughwhich passes one of the screwsd 23, 24 to clamp the pole piece to itsappropriate magnet pole.- At the junction of the base with the upright,I have struck out a lug 41 which lug cooperates with the correspondinglug on the cooperating pole piece. That is to sav, the pole pieces 19are made in leftfand right pattern with the lugs meaeee of the uprightportion being-riveted over slightly t'o hold the windings inf/place. Inthe assembly of the parts, the windings are assembled upon the polepieces and then the pole pieces, the magnets and the posts are assembledupon the 'mounting plate 16.

.Now, it will be observed that in drawing the screws 234 and 24 tight,there may be a tendency to buckle the mounting plate 16, particularly inthe vertical line 4 4 shown in Fig. 1,v and it is to prevent this thatthe reenforcing or stamping at 26 has been resorted to. There is not asmuch tendency to distort the lower part of the plate 16 since theterminalblock 28 Offers' resistance to bending in one direction. I findthat the stamping and offsetting of the portion 26 considerablystrengthens this plate without interfering witlr its function as a toneplate.

Afterthe parts have been assembled in place and the washers 29 and3()connected to the windings 44, the air gap between the upright ends ofthe polepieces 19 and the diaphragm 15 is carefully ground to apredetermined size, the raised rim of the tone plate upon which thediaphragm seats, be-

ing also ground off in a-parallel plane so' as to afford a good seat forsaid diaphragm 15.

" It will'be seen from the above that I have provided a structure whichis easily and inexpensively manufactured and assembled and which iscapable of manufacture with the assurance of uniformity of the product.The windings 44 are preferably 4made of enameled Advance wire so thatthe resistfr ance thereof does not change appreciablywith temperature.

The employment of the auxiliary magnetic gap 42, which is illustrateddiagrammatically in Fig. 9, gives the receiver unique characteristics.Due to the auxiliary gap 42, there is not the tendency for the magnet 35to` weaken if permitted to remain without a` proper keeper. Also due tothis auxiliary gap, the upper ends of the'pole pieces are much freermagnetically to have the flux therethroug vchanged by the windings 44,than would-be the case where such auxiliary gap were not provided. Thatis to say,

assume that the flux of the permanent magnet 35 is a constant, a certainportion of the same will pass through the main air gap through thediaphragm 15 and back to the shown or described.

`cooperating pole piece, and another part of the magnetism'will tend topass through the aii ap 42. j

O viously if the iux through the upper ends oi' the pole pieces abovethe gap 42 is to be varied, some means should be provided for permittingsuch variation to occur with a minimum of effort. That is to say, if noauxiliary gap were provided then the magnet lines of force could bechoked out of the pole pieces only bymain strength of the current goingthrough the windings 44. In the structure of my invent-ion it is notnecessary :t'oi the luxto be changed in the permanentl magnet 35, thepath which the liuxv takes being merely shifted. lHence, upon a veryslight opposition to the liow of magnetism up through the main air gap,

'suoli magnetism may be diverted lto the auxiliary gap 42.4 'llhus avery sensitive receiver is provided and the condition of sensitivity isinherent in the structure. The auxiliary gap 42 is greater than the sumof the two main air gaps. Also, there is less danger of the permanentmagnet 35 weakening through the course of time, because of the auxiliarygap 42.

l do not intend to be limited to the details ll claim:

1. lin a telephone receiver,.a shell ofshee metal drawn vinto a cup,said cup having the rim thereof iared out, said rim having its peripherythreaded, the edge of theI cup forming a narrow seat, a tone plateformed of relatively thick sheet aluminum having a plane peripheral edgeforming a relatively wide seat for a diaphragm, a diaphragm on saidseat, a capthreaded on said cup and clamping the edge of the tone plateand the diaphragm, said tone plate having itsk central portion depressedslightly below the diaphragm seat, and a magnet system `mounted upon thetone plate and projecting through the same into proximity to thediaphragm. f t l f 2. ln combination, a cup, a cap threaded to the edgeof the same, a sheet metal tone plate comprising a planar rim providinga wide seat, a diaphragm on said seat, the body of' the tone plate beingdepressed a short distance below the -rim,.. said Abody having anopening through the. center, a magnet system clamped to the plate andprojecting through said opening, a terminal block mounted on saidplate,-a screw passing through said terminal block and threaded intosaid tone plate, said tone plate having integral lugs struck down intocontact with the vblock to hold the same against turning. f`

3. A tone plate comprising a sheet of aluminum having a Araised fiatedge forming a diaphragm seat, said plate having a central aperture forthe magnet system, the

edge ot' lthe aperture being ycompressed. by stamping to harden Jrhesame.

4. A tone plate comprising a sheet of aluminum having a raised flatedgeorming a diaphragm seat,.said plate havmg a central aperture fgr themagnet system, the

edge of the aperture being reinforced, and integral lugs struck downfrom the edge ot the aperture for engaging aterlninal block.`

5. A magnet pole piece for a watch case receiver comprising .a sheetmetal stamping consisting of a base portion adapted to' engage the poleof a permanent magnet and an end. portion lying in a plane atsubstantially right angles to the plane of the base portion,` said endportion having an integral lug struck therefrom and. extended in theplane ofw the base portion and forming a an upright portion lying in aplane at subl stantially right angles to the plane of the base portion,said upright portion having an integral lug struck from the centerthereof and extending in the plane of the base portion and forming aseat for the end of the winding for sai pole piece.

7. In oombination,.a tone plate having a raised rim forming a diaphragmseat, a central opening, a magnet system comprising a horse-shoe magnet,posts between the ends of the magnet .and the plate, pole piecesprojecting from the ends of the magnet through said opening, a screw foreach pole piece passing through the adjacent end of the magnet, throughthe post and thread,

ed into the plate.

4 8. In combination, a tone plate having a spacing said pole pieces. y L9. In combination, a tone plate having a raised rim forming a diaphragmseat, a central opening, a magnet system comprising a'horse-shoe magnet,posts betweenthe ends of the magnet and the plate, pole pieces Iprojecting from the ends `of the' magnet through-said opening, a screwfor each pole piece passing through the .adjacent end of.

the magnet, throughv the postv and threaded into the plate, said polepieces comprising base portions which are clamped fiat against the endsof the magnet and upright portions disposed centrally of. the toneplate, said pole pieces having lugsstruck out of the upright portionsand extending towards each other, windings having heads supported bysaid lugs, said lugs projecting towards each other and forming ali airgap between them of greater extent than the air gap of said pole pieceswith their co-operating diaphragm.

10. lin combination, a permanent magnet having pole pieces, said polepieces having base portions and upright portions, lugs struck out of theupright portions extending in the plane of the base, windings for theupright portions, said windings c-omprisin heads supported upon saidbase portions an upon said lugs.

11. 1n combination, a permanent magnet having pole pieces, said polepieces having base portions and upright portions, lugs struct: out oithe upright portions extending in the plane ofthe base, windings for theupright portions, said windings comprising heads supported upon saidbase pbrtions and upon said lugs, said lugs extending towards each otherand forming an auxiliary gap ot greater spacing than the diaphragm gapand substantially less, than the spacing of the pole pieces.

12. ln combination, 'a tone plate comprising` a sheet of relativelyvsoft non-magnetie material having a raised rim forming a din aphragmseat, said plate having a central naaaeee aperture, a termlnal blockadjacent the aperture, a pair of terminals at the ends of said block, acentral screw passin through the block and into the plate, sai platehaving lugs struck up from the edgesl of the aperture to engage the endsof the block.

13. lin combination, a permanent magnet,

magnet.

14.1n combination, a permanent magnet, a tone plate having a Acentralaperture, supporting posts between the poles of the magnet and the toneplate, screws passing through the poles and through the posts andsecured to the tone plate, a terminal block having a central screwpassing through said tone plate between said screws, which supports themagnet.

15. lin combination, a permanent magnet, sott iron pole piecescomprising lat bases and parallel upright portions, and an auf-:iliaryair gap formed by striking out lugs from the parallel 11p-rightportions.

ln witness whereof, 1 hereunto subscribe my name this 26th day ofNovember, 1924-.

' JAMES A. STIRING.

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